T-Mobile Q4 Growth Tumbles Despite Google Phone (GOOG)

T-Mobile says Q4 subscriber growth slowed despite an exclusive on the G1, Google's (GOOG) first Android-powered phone. T-Mobile signed up 621,000 net new subscribers during Q4, down more than one-third from Q4 2007, when it signed up 951,000 net subscribers.

T-Mobile didn't disclose G1 sales, but said 40% of the phones it sold in Q4 -- to existing and new customers -- were smartphones.

That's good for its average monthly revenue -- smartphone customers are often required to sign up for Internet service plans. But it looks like the G1 hasn't been as strong for T-Mobile as Apple's (AAPL) iPhone has been for AT&T (T), or RIM's (RIMM) BlackBerry Storm for Verizon (VZ).